92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Tuesday, 24 January 2012: 8:45 AM
Investigating the Impact of Alaskan Fire Emissions on Convective Systems Over the Eastern U.S. in Regional Simulations Driven by a GCM with Explicit Embedded Convection
Room 244 (New Orleans Convention Center )
Zhan Zhao, SIO/Univ. Of California, La Jolla, CA; and G. kooperman, M. S. Pritchard, L. M. Russell, and R. C. J. Somerville

Alaskan forest fire emissions can be transported over long distances that have the potential to effect convective systems as far as the eastern coast of North America. However, regional climate simulations run at convection-resolving resolution can not encompass the entire continent and simultaneously capture both the source region and impact area. Coupling the Multiscale Aerosol Climate Model (MACM), a superparameterized branch of the Community Atmosphere Model Version 5 (CAM5), to the Weather Research and Forecasting model with Chemistry (WRF-Chem) provides a unique opportunity to realistically include lateral inflow of long-range transported pollution plumes to the regional model domain. The use of embedded cloud resolving models in each global-scale grid cell of MACM improves many convectively coupled processes potentially important to the vertical positioning and composition of the long-range transported aerosol, which could subsequently improve the WRF-Chem simulation of aerosol-cloud interactions. To evaluate the benefits of using MACM to drive regional simulations, we investigate a boreal forest fire plume transport event in the summer of 2004 when a significant amount of forest fire aerosols from Alaska/western Canada were observed in both the boundary layer and free troposphere over the eastern United States. Forest fire emissions transported and processed in both MACM and standard CAM5 are separately used as lateral boundary conditions flowing into a WRF-Chem domain situated over the eastern United States. We compare the effect these two sets of boundary conditions have on aerosol-cloud interactions over this region, focusing on simulated clouds and precipitation. Ground based lidar and in situ aircraft measurements from the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) field campaign are used as a baseline for model evaluation.

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